Process for the production of plastics and lacquer resins from basic nitrogen-containing glycidyl compounds and dicarboxylic anhydrides

ABSTRACT

This invention concerns a process for increasing the hardening rates in the preparation of epoxide resins using dicarboxylic anhydrides as hardening agents. The increase in hardening rates is achieved by reacting mixtures of basic nitrogen-containing glycidyl compounds with di-carboxylic anhydrides. An optional aspect of the inventive process is to conduct the above reaction in the presence of alkyd resins and/or solvents.

United States Patent [191 Wiillner et a1.

[451 Oct. 1, 1974 [73] Assignee: Deutsche Texaco Aktiengesellschaft,

- Hamburg, Germany [22] Filed: Dec. 6, 1972 [21] Appl. No.: 312,459

(2 Related U.S. Application Data [62] Division of Ser. No. 62,692, Aug. 10, 1970.

[52] U.S. Cl...... 260/22 EP, 117/161 ZB, 260/22 T,

260/37 EP, 260/47 EN, 260/47 EP, 260/835 [51] Int. Cl C09d 3/66 [58] Field of Search 260/22 EP, 835, 78.4 EP,

260/37 EP, 2 EP, 75 N, 75 EP [56] References Cited UNITED STATES PATENTS 2,884,406 4/1959 Wegler et a1. 260/47 3,639,314 2/1972 Cherubim et a1. 260/835 X Primary Examiner-William H. Short Assistant Examiner-T. Pertilla Attorney, Agent, or Firm-T. H. Whaley; C. G. Ries [5 7] ABSTRACT This invention concerns a process for increasing the hardening rates in the preparation of epoxide resins using dicarboxylic anhydrides as hardening agents. The increase in hardening rates is achieved by reacting mixtures of basic nitrogen-containing glycidyl compounds with di-carboxylic anhydrides. An optional aspect of the inventive process is to conduct the above reaction in the presence of alkyd resins and/or solvents.

4 Claims, No Drawings PROCESS FOR THE PRODUCTION OF PLASTICS AND LACQUER RESINS FROM BASIC NITROGEN-CONTAINING GLYCIDYL COMPOUNDS AND DICARBOXYLIC ANHYDRIDES This is a division, of application Ser. No. 62,692, filed Aug. 10, 1970.

This invention concerns novel hardening compositions, their use in hardening epoxides and the uncured and cured resins produced therein.

More particularly, this invention relates to mixtures of dicarboxylic anhydrides and basic nitrogencontaining glycidyl compounds which are used to harden epoxides compositions as well as epoxides in the presence of alkyd resins and/or solvents.

BACKGROUND OF THE INVENTION Epoxy resins are resinous materials containing epoxy groups. These resins are widely used in protective coatings and films, as structural plastics, and as adhesives among other applications.

Epoxy resins are thermosetting materials which may be converted into durable, crosslinked polymers by the utilization of hardening or curing" agents with or without the application of heat. Simple heating of epoxy containing materials does not effectively cure the resins effectively. In the plastics industry the epoxycontaining resins are normally blended with a specific hardener by the user to obtain the desired physical properties.

Desirably, hardening agents utilized for epoxide resins should combine certain characteristics for widespread commercial acceptance. The most important of these are: being in the form of low viscosity liquids, having high reactivity at elevated temperatures yet having relatively good pot life stability at storage temperatures of about 20C.

Hardeners in the liquid state at room temperature offer the advantage that they can frequently be used without the need for solvents, and without the need to heat the polymer mixtures to insure uniformity. Heating increases the risk of premature curing. Low viscosity is an especially desirable attribute for coating applications in that it permits deeper penetration of the substrate treated, increases wetting properties and allows the incorporation of large quantities of inexpensive fillers into the formulation. Rapid and high activity of the hardeners at elevated temperatures permits rapid processing cycles, while good pot-life" stability at 20 to 30C. permits safe long-term purchasing and storage of the epoxy resin in curable form.

A very large number of chemical compounds have been used as hardeners or curing agents to convert epoxy resins into useful hard, infusible, cross-linked polymers. These include polysulfides, amines, multifunctional alcohols, carboxylic acids, phenols and dicarboxylic anhydrides (anhydrides or dibasic acids) among others. While all of the above may be used. the most commonly employed hardeners are the dicarboxylic anhydrides such as phthalic anhydride, dodecylsuccinic anhydride, pyromellitic dianhydride, their isomers and their derivatives, among others.

While dicarboxylic anhydrides contribute to lowering the viscosity of the epoxide resin mixtures and produce hardened polymers having good final properties. they have a great drawback in that they are very sluggishly reactive even at moderately elevated temperatures. This is particularly exhibited in the case of liquid resinhardener mixtures comprising low-viscosity and hence low molecular weight epoxide compositions which ordinarily require a relatively long time before being completely hardened. For instance, a reaction mixture comprising 1 epoxy equivalent of 4,4-dioxy-diphenylpropane diglycidyl ether and 0.9 moles of a liquid isomerized product of tetrahydrophthalic anhydride is not hardened after heating for a period of 16 hours at a temperature of C. In fact, it is difficult to see even an initial hardening of the resin mixture. While small amounts of N-glycidylalkylamines such as N-diglycidylbutylamine may be added to accelerate the sluggish hardening reaction, in many instances even the addition of this amine to the reaction mixture does not produce a mixture considered to have a sufficient reactivity.

.Recently it has been found that many of the deficiencies and disadvantages encountered when dicarboxylic anhydride type materials are used to harden commonly used epoxide resins can be overcome by utilizing mixtures of N,N-diglycidyl-N,N'-dialkyl-l,3-diamino-2- hydroxypropane and N-diglycidyl-alkyl-amine* as the epoxide starting materials. Not only are the hardening and gel rates of the epoxide reaction mixture improved over what is obtained when a single N-diglycidyl compound is hardened with the same anhydride, but they are superior even to those anhydride hardened resins prepared from diglycidyl compounds of 4,4-dioxyphenylpropane. In addition, the laquer resins produced from the resins of this invention are of high gloss, have a fair resistance to water and chemicals and a good final hardness. The resins produced from these mixtures have good strength properties. N-diglycidyl isopropylamine and/or diisopropyl-l,3-diamino 2-hydroxypropane are disclosed to increase the viscosity of alkyd resins to be utilized as lacquer resins in Ser. No. 750.746 filed in the US. Aug. 7. was.

In the preferred process, the above-described advantages, accelerated hardening rates and substantially diminished hardening times are obtained in the reaction of N-glycidyl compounds with dicarboxylic anhydrides by using. as starting materials, epoxide reaction mixtures comprising 10 to weight percent of N,N'- diglycidylN,N -dialkyll ,3-diamino-2- I hydroxypropanes, and 90 to 10 weight percent N- diglycidyl-alkyl-amine, said mixtures containing at least a hardening quantity of dicarboxylic anhydride.

Further desirable process and product variations include incorporating alkyd resins with optional solvents and additives for preparing lacquer resin compositions useful as air-drying lacquers or stoving lacquers.

In other process alternatives, in some instances it is convenient to subject the epoxide resin compositions to precondensation with one or more suitable reactive compounds such as polyhydric phenols or dicarboxylic anhydrides. An illustration of a typical precondensation reaction comprises condensing from about 0.1 to 0.3 moles of a composition such as dimethylhydantoin with one or both of the epoxide materials. Precondensation reactions such as these, when carried out prior to hardening, many times have a surprising and improved effect on the properties of the epoxide resin compositions and can extend their usefulness for varied applications.

Yet additional process and products include starting materials for the preparation of cast molded materials, e.g., for centrifugal casting products when powdered quartz or other inert fillers are incorporated into the epoxide mixture.

The epoxide resin compositions of this invention may also be utilized as adhesive agents or in the modification of plastomers, duromers and elastomers.

In order to more clearly illustrate the scope of the inventive concept, the following supplemental disclosure is submitted:

A. DICARBOXYLIC ANHYDRIDE TYPE HARDEN- ERS This is a generic term used throughout this disclosure to describe the anhydrides of dibasic acids, their mixtures, derivatives and isomers which are utilized as hardening agents in this invention. These hardeners comprise liquid or semi-solid anhydrides preferably in the liquid state. Illustrative anhydrides include isooctenyl succinic anhydride, dodecyl succinic anhydride, the liquid isomerized product of tetrahydrophthalic anhydride or isomerginic acids among others. B. BASIC NITROGEN-CONTAINING GLYCIDYL COMPOUNDS This is the generic term used throughout this disclosure to describe compounds containing at least one epoxy group and at least one basic amino group. These are known compounds often available commercially, whose preparation is documented in the scientific and patent literature. Suitable aromatic N-diepoxy compounds which may be hardened in the inventive process include those disclosed in German Patent No. 1,132,148 (Frank et al) wherein free primary aromatic amines are reacted with epichlorohydrin and treating the reaction product with aqueous caustic, preferably at room temperature, using aromatic solvents such as benzene or toluene if desired. Similarly, utilizable nitrogen-containing basic aliphatic diepoxides may be obtained by reacting free primary aliphatic amines. with epichlorohydrin and treating the product with aqueous caustic as before. The detailed description of these preparations is disclosed in German Patent No. 1,132,146 (Frank et al.). The preparation of other suitable nitrogen-containing glycidyl compounds is disclosed in German Patent No. 1,206,915 (Haydn et al.) which describes the preparation of aromatic epoxides by reacting- N-alkyl-N-- arylamines or aromatic amines with epichlorohydrin in the presence of a solvent that forms azeotropic mixtures with water at temperatures below 100C.

While the above-described nitrogen-containing glycidyl compounds and many others may be satisfactorily hardened, as is many times the case in any large group or class, some members of the class offer advantages over the class as a whole and are therefore favored. In this instance the favored basic nitrogen-containing glycidyl compounds are selected from the group consisting of N,N-diglycidylN,N'-dialkyl-1,3-diamino-2- hydroxypropane and N-diglycidyl-alkyl-amine, wherein the alkyl groups may contain one to six carbon atoms. The compounds preferred for hardening comprise mixtures of N-diglycidyl isopropylamine (abbreviated as DIPA) and/or N,N'-diglycidyl N,N'-diisopropyl-l ,3- diamino-2-hydroxypropane (abbreviated as DDDI-I).

The mixture of these two nitrogen-containing glycidyl compounds are preferred because when used together in the presence of dicarboxylic anhydride-type materials they substantially reduce hardening times compared to the hardening times obtained using either basic N-glycidyl compound alone with the same anhydride-type materials. C. OPTIONAL MODIFICATIONS AND ADDITIVES As has been indicated earlier the instant invention lends itself to certain modifications and optional embodiments. For example, it is possible to substantially modify the properties of the epoxide resins being prepared by the inventive concept. A specific embodiment concerns improving the flexibility and lengthening the pot-life of the resins by mixing them with polyhydric glycidyl compounds of slower reactivity of the type illustrated by 4,4'-dihydroxy-diphenylpropane (abbreviated as DIAN). Usually, when from 5 to 10 parts by weight of DIAN is incorporated into 95 to parts by weight of the basic nitrogen-containing N-glycidyl compounds the desired prolongation of pot-life is obtained. However, much larger proportions of DIAN to the nitrogen-containing glycidyl compounds may be used to obtain resins having properties like DIAN but with improved hardening properties in the resins. For instance, from 5 to 10 parts by weight of the mixture of basic nitrogen-containing glycidyl compounds can be added to to 90 parts by weight of DIAN to produce a substantial increase in the rate of hardening in the predominantly DIAN resin mixture, without substantially compromising the properties of the resin.

Similarly, alkyd resins such as phthalic anhydride ricinene-soy oil-alkyds (42 percent by weight soy oil 38 percent by weight of the phthalic anhydride) can be incorporated into the basic nitrogen-containing glycidyl compound to form a hardened film useful for coating applications when isomerized phthalic anhydride is used as the hardening agents. The alkyd resins which are employed for these modifications are known materials and are prepared by the conventional condensation of polyols with polybasic acids and/or anhydrides described in the technical and patent literature. Inert particulated fillers such as powdered quartz, mica, diatomaceous earth, etc., may also be added to the uncured mixture to obtain resins suitable for cast molding techniques such as centrifugal casting.

D. REACTION CONDITIONS, RATIO OF REAC- TANTS, TEMPERATURE, ETC.

1. Ratio of components The quantity of dicarboxylic anhydride-type compound to nitrogen-containing glycidyl is relatively non-critical, as long as at least a hardening amount of anhydride is present. This comprises about 0.5 to 1.0 moles of anhydride per equivalent of epoxide content. This is ordinarily sufficient to produce hardened resins within about an hour at temperatures between to C. when dodecyl succinic anhydride is utilized as hardener with the preferred epoxide mixture. A narrow ratio of from about 0.8 to 1.0 moles of anhydride for each epoxide equivalent of the basic nitrogen-containing glycidyl compound produces hardening at the above temperatures within 30 minutes or less and hence is preferred.

' peratures are in centigrade and all 2. Temperatures The temperatures required for hardening .are not critical. Ordinarily temperatures ranging from about 50 to 140 C. are satisfactory with temperatures ranging from about 60 to 120 C. being preferred. As indicated earlier, curing times at about 100 to 120 C. ordinarily are less than an hour, usually from to 30 minutes. E. TESTING, STRENGTHS, ETC.

The measure of hardness obtained in the resins of this invention is that referred to as Konigs pendulum test, a known procedure described in the literature*. *Disclosed in DIN 53 157 The method of making flexura] strength measurements given in the tables of this invention is .also a known procedure described in the literature.** "Disclosed in DIN 52 362 (January 1955 and November 1961) In order to illustrate the workings of the inventive process as fully as possible the following illustrative examples are submitted. Unless otherwise stated, all temparts and percentages are by weight rather than volume. EMBODIMENT I HARDENING OF A NON-NITROGEN-CONTAINING GLYCIDYL COM- POUND DICARBOXYLIC ANHYDRIDE OF THE PRIOR ART.

To a conveniently sized reaction vessel equipped with both heating and stirring means is charged a thoroughly mixed admixture of l epoxy equivalent of 4,4-

HARDNESS,

dioxy diphenyl-propanedglycidyl ether and 0.9 moles FLEXURAL 6 SOLVENT-FREE EPOXIDE RESIN MIXTURES CONTAINING DICARBOXYLIC ANHYDRIDES WlTH ONE OR TWO N-GLYCIDYL COMPOUNDS.

Three tests were run, blending 1 gram of the designated epoxide thoroughly with dicarboxylic anhydride. The mixture'sof epoxides and anhydrides were tested as to their gel time, and subsequently spread as films of 1 thickness on glass plates which are heated to the designated temperatures. Test 1 utilizes dodecyl succinic anhydri de plus DIPA, and the anhydride plus a 5050 ratio 0f DIPA and DDDH. Test'2 utilizes mixtures of isooctenyl succinic anhydride plus DIPA and the anhy-' dride plus the 50-50 DIPA-DDDH mixture. Test 3 utilizes a liquid isomerized product of tetrahydrophthalie anhydride with DIPA, and the same anhydride plus the 5 DlPArDDD m xtu As Ta le which lows indicates, in all instances gel times and hardness values of the mixture of anhydride plus both DIPA and DDDH are substantially improved over those obtained with anhydride plus DIPA alone. It will also be noted that in all instances hardening times of both DIPA and DlPA-DDDHmixtures are 1 hour or less at temperatures ranging from 60 C. to 120 C. This rapid hardening time obtained using the inventive concept is a substantial improvement over hardening times obtained, when a conventionally employed glycidyl compound such as 4,4'-dioxy-diphenyl propane diglycidyl ether is hardened with a dicarboxylie anhydride as described in Embodiment I.

TABLE I Test No. Dicarboxylic Epoxide Compound Addition Hardening gel time Hardness anhydr. (per (perl epoxy conditions at l00 C measured by 0.9 mole) equivalent) in min. Konigs test with pendulum in sec.

1 dodecyl DIPA min. 6

succinic at anhydride 120 C.

do. Mixture of DIPA/ do. 17 131 DDDH in /50ratio 2 isooctenyl DIPA 30min. 18 1 l0 succinic at anhydride 120 C do. mixture of DIPA/ do. 7.5 184 DDDH in 50/50 ratio 3 liquid DIPA min l6 l9 isomerized product at of tetrahydro- 60 C. phthalic anhydride do. mixture of DlPA/ do. 4.5 U7

DDDH in 50/50 ratio ME V H A of a liquid isomerized product tetrahydrophthalic anhy- 1 EXAMPLE 2. dride. The mixture is heated to 80C. and this temperature is maintained for 16 hours. At the end of this time not even an initial hardening of thereaction mixture canbe noticed. This is illustrative of the sluggish reactivity of theanhydrides which are the great drawback of the anhydride as hardeners for ordinary epoxides of the prior art.

EXAMPLE 1. I E EEQLQN H BQENJNG RATES OF VARIOUS .HARDENING OP WET FILMSCOMPRISING EP- 7 jOXlDE RESIN, DICARBOXYLIC ANHYDRIDE AND ALKYD RESIN.

Using the blending procedure of Example 1, different admixtures of DIPA and DDDH, anhydride and alkyd resin are heated at 80 C. to determine the effect upon hardening time and hardness of the resultant film.

Table II shows that process permits the inclusion of alkyd resins without substantially compromising hardening time. k W

7 TABLE II Mixture of lsomerizcd Phthalic Hardening Hardness measured by 50 wt-% of product of anhydride- Konig's pendulum N-diglycidyltetrahydro ricinenetest in min. isoLpropylumine phthalic soy oilun anhydride alkyd O wt-Ci of (42% oil) N.N'-dig lycidyl (38% FAA) N.N-diisopropyll.3-diamino- Z-hydroxypropane 1.0 epoxide 0.9 mole 0.0 g 60 min. at 212 equivalent 80 C.

do. do. I25 g do. 184

do. do. 250 g do. 138

EXAMPLE 3. have a fair iesiaalrc'eia water anagaaarifimardfia. FLEXURAL STRENGTHS OF CAST MOLDED In addition, cast molded materials prepared from these TERlALS PREPARED FROM SOLVENT-FREE EP- F' have good l l OXIDE RESIN COMPOSITIONS AND DICARBOX Finally, the novel invention 18 relatively flexible inso- YUC ANHYDRIDES far as modifications, substitutions and variations that Three epoxide resin compositions described below 20 may be made wlthout l from the inventive l are mixed with isomerized product of tetrahydrophcept' m vanous dlscaljhmxyhc anhydrlflies thalic anhydride hardener and powdered quartz filler, and denvatwes be unhzed harderlmg cast into standard bars and thermoset by heating 16 agents wlth one or more mtlogen'cmltammg glycldyl hours at 80 C. The first composition contains only the gompoupds and hardemng reiicuon can be q g mixture of the two glycidyl Compounds and ormed m the presence of alkyd resins and/or solvents. hardener, the second is pr econdensed with 0.1 moles of Th scope f h inventive Concept i b d y y f as lrldlcatedfourth l f mined by the claims. which follow, read in conjunction batch comprises conventional epoxide composition i i h hi ifi i which has not been precondensed. This batch is also i wh i claimed heated for 16 hours at 80 C. As the data of Table ll] 1 (below) indicates, utilizable quickhardening epoxidel resins have good final properties are produced in all but the conventional epoxide batch (4). This latter did not harden at all within the heating period.

1. Rapidly hardenable epoxidealkyd resin compositions suitable for the manufacture of resins including film and cast molding applications, consisting essentially of a hardening amount of dicarboxylic anhydride material and a mixture of basic nitrogen-containing TABLE III Epoxide resin Pre-linkage Dicarboxylic Filler Flexural strength composition with anhydride in kp/sq. cm.

I epoxide isomerized for each 16 hr at 80C. equivalent product of respect. 488 mixture of tetrahydromixture wt-% phthalic 400 wt-% N-diglycidylanhydride powdered isopropylquartz amine with 50 wt-% N,N'-diglycidyl-N,N'-diisopropyl-l,3 diamino-Z hydroxypropane do. 0.l mole dian do. do. do. 527 do. 0.1 mole do. do. do. 494

dimethylhydantoin min.

dian-diglycide do. do. no hardening As the various embodiments and examples demonstrate, this invention is advantageous in both its process and compositional aspects. For instance, the novel process of this invention substantially increases the rate of hardening obtained when dicarboxylic anhydride type of materials are used as hardening agents for epoxide materials. Further, the novel process permits the hardening to be conducted in the presence of substantial quantities of alkyd resins and/or solvents.

in its compositional aspects, the inventive process is advantageous in that the more rapidly hardened epoxide mixtures have favorable final properties. For example. lacquer resins produced from the inventive nitrogen-containing glycidyl compounds are of high gloss,

glycidyl compound consisting essentially of atleast one compound selected from the group consisting of N,N'- .qatveiqy -u.u'a ani-i .s-q a hydroxypropanes, N-diglycidyl-alkyd-amines, and mixtures therein, and at least one alkyd resin consisting essentially of a polyol-phthalic anhydride-ricininesoybean oil mixture wherein said alkyd resin mixture consists essentially of 42 percent by weight of soybean oil and 38 percent by weight of phthalic anhydride.

2. The resin composition of claim 1 wherein an inert filler is incorporated into the hardenable composition.

' 3. A process for producing a rapidly hardenable epoxide-alkyd resin suitable upon hardening for the epoxide resin applications, including film and cast molding applications, by admixing a hardening amount of at 10 essentially of polyol, 38 percent by weight of phthalic anhydride and 42 percent by weight of ricininesoybean oil mixture. 4. The process of claim 3 wherein inert filler is incor- 9rq sdjntzth ar enahle m xture- 

1. RAPIDLY HARDENABLE EPOXIDEALKYD RESIN COMPOSITIONS SUITABLE FOR THE MANUFACTURE OF RESINS INCLUDING FILM AND CAST MOLDING APPLICATIONS, CONSISTING ESSENTIALLY OF A HARDENING AMOUNT OF DICARBOXYLIC ANHYDRIDE MATERIAL AND A MIXTURE OF BASIC NITROGEN-CONTAINING GLYCIDYL COMPOUND CONSISTING ESSENTIALLY OF AT LEAST ONE COMPOUND SELECTED FROM THE GROUP CONSISTING OF N,N''-DIGLYCIDYL-N,N''-DIALKYL-1,3-DIAMINO-2HYDROXYPROPANES, N-DIGLYCIDYL-ALKYD-AMINES, AND MIXTURES THEREIN, AND AT LEAST ONE ALKYD RESIN CONSISTING ESSENTIALLY OF A POLYOL-PHTHALIC ANHYDRIDE-RICININE-SOYBEAN OIL MIXTURE WHEREIN SAID ALKYD RESIN MIXTURE CONSISTS ESSENTIALLY OF 42 PERCENT BY WEIGHT OF SOYBEAN OIL AND 38 PERCENT BY WEIGHT OF PHTHALIC ANHYDRDE.
 2. The resin composition of claim 1 wherein an inert filler is incorporated into the hardenable composition.
 3. A process for producing a rapidly hardenable epoxide-alkyd resin suitable upon hardening for the epoxide resin applications, including film and cast molding applications, by admixing a hardening amount of at least one dicarboxylic anhydride material with a mixture of basic nitrogen-containing glycidyl compounds of at least one compound selected from the group consisting of N,N''-diglycidyl-N,N-dialkyl-1,3-diamino-2-hydroxypropanes, N-diglycidyl-alkyl amines, and mixtures therein said alkyl groups containing from one to six carbon atoms, and at least one alkyd resin consisting essentially of polyol, 38 percent by weight of phthalic anhydride and 42 percent by weight of ricinine-soybean oil mixture.
 4. The process of claim 3 wherein inert filler is incorporated into the hardenable mixture. 